Some of the most serious arrhythmias that patients can experience are the rapid and prolonged arrhythmias that come from the pumping chambers. This usually occurs when these chambers have been previously damaged and scarred, such as the after a heart attack. During these arrhythmias, there is frequently a fall in blood pressure and even loss of consciousness. Unless terminated, they can lead to fatal consequences. These arrhythmias require prompt termination which can be most readily accomplished by the application of an electrical shock across the chest. Outside the hospital, this is accomplished by an ambulance team who places paddles on the chest and delivers the shock with an external defibrillator. Implantable defibrillators use the same concept. This device, being permanently available to monitor a patient’s rhythm, can automatically and within seconds, deliver life-saving electrical energy directly to the heart. Patients who are deemed high risk for the development of these dangerous arrhythmias will often be treated prophylactically with an implanted device so that they are protected without need for intervention by emergency personnel.
These devices are called implantable cardioverter defibrillators (ICD). These are implanted in a similar fashion like permanent pacemakers. Using a large vein of the arm that passes underneath the collar bone, a wire or lead can be passed into the right side of the heart. This wire can record the electrical signals from within the heart and communicate with the device when the heart has gone into a rapid, dangerous arrhythmias. This lead is connected to the device which is then buried under the skin below the collarbone. When this device detects a dangerous arrhythmia, it delivers electrical energy through the heart to reset the heart’s electrical rhythm and heart resumes its normal electrical activity. The entire process of detection and termination of this potentially fatal arrhythmia usually lasts 6-15 seconds. This device can be highly effective and often life-saving in patients who are at risk for dying from dangerous electrical heart rhythms.